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Dry ice has been a dependable refrigeration resource for shipping many types of perishable goods, including pharmaceuticals (as long as, in the case of biologics, the -60° material is kept separate from vaccines and other products that can’t be frozen). But with the introduction of new, high-tech and energy-efficient cargo jets like the Boeing 777, that practice is becoming a risk, says FedEx’s Richard Smith.
Smith, whose company is refurbishing its fleet with modern aircraft including the 777, says that the newest energy-efficiency designs of these aircraft reduce the amount of fresh air flowing from the engine into the aircraft. And with better insulation of cargo holds and more-precise temperature management of the cargo hold (including the ability to maintain a set temperature in the cargo hold), the possibility of too much carbon dioxide gas (the byproduct of dry ice becoming warm) in the aircraft’s interior—including the pilot cabin—becomes a risk.
FedEx has been conducting extensive research on aircraft atmosphere and temperature control, says Smith, but already, the company has been forced to reallocate some deliveries that had too much dry ice (compared to other, non-refrigerated freight) to avoid the risk of CO2 contamination. (It’s worth noting here that Smith is talking almost exclusively about cargo jets, and not passenger jets that take small-parcel freight.)
In discussions with the Federal Air Administration, FedEx has noted that the FAA’s formula for the rate of dry ice sublimation (warming) is extremely conservative, and could be changed without putting pilots at risk. But so far, there has been no change in this formula. “There are supply chain implications of this for the life sciences industry,” he says. “We’ve already had adjustments to make, as will other carriers.”